Ultrasonic surgical instruments are finding increasingly widespread applications in surgical procedures by virtue of the unique performance characteristics of such instruments. Depending upon specific instrument configurations and operational parameters, ultrasonic surgical instruments can provide substantially simultaneous cutting of tissue and hemostasis by coagulation, desirably minimizing patient trauma. The cutting action is typically effected by an end-effector at the distal end of the instrument, with the end-effector transmitting ultrasonic energy to tissue brought into contact therewith. Ultrasonic instruments of this nature can be configured for open surgical use, or laparoscopic or endoscopic surgical procedures.
Ultrasonic surgical instruments have been developed that include a clamp mechanism to press tissue against the end-effector of the instrument in order to couple ultrasonic energy to the tissue of a patient. Such an arrangement (sometimes referred to as an ultrasonic transector) is disclosed in U.S. Pat. No. 5,322,055, hereby incorporated by reference.
In previous ultrasonic instruments, the waveguide of the instrument, through which ultrasonic energy is directed, is typically provided with one or more ring-like members for acoustically dampening the waveguide, and isolating the waveguide from surrounding components. Such isolation members are typically provided at one or more nodes of longitudinal vibration of the waveguide, and are typically constructed of elastomeric material, such as silicone rubber. Isolation members of this type desirably prevent loss of vibrational energy from the waveguide which can occur under side-loading or bending conditions which might otherwise cause indirect contact of the waveguide with an associated component positioned thereabout.
In ultrasonic surgical instruments heretofore known for endoscopic applications, the outside diameter of the elongated endoscopic portion of such instruments has been on the order of 10 mm. As such, it is ordinarily been possible to provide suitable isolation members for the waveguide of such instruments, while still providing a waveguide having a sufficiently large cross-section for the desired rigidity and for delivery of the desired level of ultrasonic energy without excessive heating of the waveguide.
Continued development of ultrasonic surgical instruments has desirably resulted in instruments having even smaller endoscopic portions, on the order of 6 mm in diameter or less. When configuring ultrasonic instruments of this relatively small size, it is important that the desired acoustic dampening of the waveguide be effected, while still providing the waveguide with a cross-section which is as large as practicable. Problems in isolating the waveguide can be particularly exacerbated in ultrasonic instruments configured to effect clamping of tissue against an end-effector of the instrument, since such clamping creates bending moments within the waveguide flexing the waveguide from its normal, unloaded configuration.
The present invention is directed to an improved support member for an ultrasonic surgical instrument, with the support member of the present invention particularly suited for use in instruments configured for endoscopic applications having relatively small cross-sections.